Is this correct? In my post today I will attempt to answer this question.

First, while generally healthier people seem to have healthier brains, the physical exercise effect on the brain seems to be independent of other things. One of the most important development in neuroscience was when the official dogma claiming that there was no neurogenesis (production of new brain cells) in the adult brain was toppled. Now we know that the brain is “plastic” meaning that, under the right circumstances, the brain can change in terms of both producing new cells and getting more cells connected to each other.

One of the places where neurogenesis has been shown to occur in the adult brain is the dentate gyrus, a strip of grey matter placed deep down in the brain. The dentate gyrus is a part of the hippocampus, the main memory structure, and has been shown to play a role in the forming of new memories. What can the dentate gyrus teach us with regards to physical exercise?

Following a series of extremely thought provoking experiments researchers from the Gage laboratory at UCSD concluded that exercise leads to the production of new brain cells in the dentate. First the researchers found that mice housed in an enriched environment (a larger cage with toys, tunnels, and more opportunity for physical activity, learning, and social interaction than in standard bare cage) have an increased number of new neurons in the dentate gyrus.

The enriched environment is a mice equivalent of not only healthy but good living: leisurely enjoying life, getting both physical and intellectual stimulation, socializing with friends. Now, the fact that new neurons were produced was a big enough news in itself but the Gage group did not stop there. Their next goal was to figure out if neurogenesis was the result of a sum of factors acting together (i.e. the enriched environment) versus a specific effect of individual factor. So, they first dissected the enriched environment in a number of “sub” environments. In their next experiment they placed the mice in a “learning environment” where they had access to a maze, a “physical exercise environment” where mice had unlimited access to a running wheel, in addition to enriched and standard (empty cage) environments. Then they compared the groups in terms of behavioral performance and eventually looked at their brains.

Their conclusion was anything but expected: while both enrichment and wheel running led to improved spatial memory function only physical exercise in a running wheel also promoted neurogenesis and enhanced the survival of newborn neurons in the dentate gyrus.

Bottom line: exercising seems to literally mean “exercising the brain”.

So, in lieu of conclusion, till next I wish you all happy trails (and I don’t mean it as just trails on the paper in a paper and pencil memory task)!

Adrian Preda, M.D. is an Associate Professor of Psychiatry and Human Behavior in the UC Irvine School of Medicine’s Department of Psychiatry and Human Behavior. His expertise in human behavior, psychology and spirituality is based on years of experience working as a psychiatrist, psychotherapist, teacher and researcher in a variety of academic clinical and non-clinical settings. He also teaches the UC Irvine Extension class The Mind that Changes the Brain: Wellness in the Second Millennium.
References:

van Praag H, Christie BR, Sejnowski TJ, Gage FH (1999) Running enhances neurogenesis, learning, and long-term potentiation in mice. Proc Natl Acad Sci USA 96: 13427–13431

van Praag H, Kempermann G, Gage FH (1999) Running increases cell proliferation and neurogenesis in the adult mouse dentate gyrus. Nat Neurosci 2: 266–270.

Farmer J, Zhao X, van Praag H, Wodtke K, Gage FH, Christie BR (2004) Effects of voluntary exercise on synaptic plasticity and gene expression in the dentate gyrus of adult male Sprague-Dawley rats in vivo. Neuroscience 124: 71–79

Related reading:

- Physical Exercise and Brain Health

- Art Kramer on Why we Need Walking Book Clubs

And one thing is clear, he points out: “the brain really likes it when it’s asked to be “active”. Passive audiences, which are spoon fed information, score less well when tested on retention and understanding of the presented material than audiences that were kept engaged through the process.”

So, will you write a comment below and contribute to an engaging conversation? Thoughts? reactions? questions?
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Don’t ignore plain old common sense.

Brain Lessons Part 1

– By Adrian Preda, M.D.

Let me start with a list of common biases: expensive is better than cheap, free is of dubious value (why would then be free?), rare is likely to be valuable, and while new is better than old, ancient is always best. Which explains a common scenario that is reenacted about twice a week in my office. It starts like this: a patient shows me a fancy looking bottle of the brain supplement of the week: ancient roots with obscure names mixed together in another novel combination which you can exclusively find in that one and only store (rarity oblige!). And not to forget: it ain’t cheap either! Of course, there it is, the perfect the recipe for success: ancient yet new, rare and expensive. It got to be good! But is it, really?

The problem with recommending physical exercise when it comes to brain fitness is that is doesn’t have any of the glamour traits I have just mentioned: it’s been around for a long time – so there is nothing new and exciting about it, there is no fancy name or exclusive label marketing it and, worst of all, it is as cheap as cheap can be: not only free but also available in unlimited supplies.

So when I tell my patients that the single most important thing they need to pay attention to when it comes to keeping their brain in shape is exercise I invariably get a “really, and you needed to get an MD to tell me this?” look. Nowadays everybody seems to know that physical exercise is good for the brain. Big news they say. And they needed to study that? Duh?

For most it’s no big surprise to find out the people who have a physically active life style have a decreased risk of Alzheimer’s dementia or the number of blocks one walks everyday appears to inversely correlate with the rate of cognitive decline later in life. It sort of makes sense to assume that has to be the case. Here are a few well established facts.

First of all, regular physical exercise correlates with improved health – meaning less risk for high blood pressure, metabolic problems (cholesterol, lipids and glucose dysregulation) and weight gain, which is all good for the brain. A healthy brain needs a healthy environment, doesn’t it? Or to put it in a slightly different way: an unhealthy environment would not be good for the brain, wouldn’t it? I think we would all agree on that one.

Now, would a healthy environment not only protect but also improve the brain structure and performance? Would it also promote the growth (if possible) of the brain? The answers to such questions are less obvious. For example we know that not all healthy people end up with “good brains”. Well, why is that? Specifically, when it comes to physical exercise then are there such things as a minimal dose of exercise that can result in positive brain effects? And is there a maximal or “toxic” dose of physical exercise which may in fact hurt the brain? Is all physical exercise equally good for the brain or do different physical exercise routines differ in terms of their brain effects? I put those questions on the table and the chance is that I got the “duh” people’s attention.

First, let me say that to scientists the physical exercise question is no different that any other scientific question. Scientists tend to be a skeptical bunch and as such they like to always point out that correlation does not necessarily imply causation. Take the old active people who didn’t get Alzheimer’s example. One possibility is that their consistent exercising keeps them from getting Alzheimer’s. But what is it that got them to exercise more in the first place? Could it be that their brains were equipped with the sort of gear that gets one excited about pushing themselves a bit, which would then result in these fellows being more prone towards doing physical things to start with? Then they will be more active physically but that is because their brains were wired differently from the gecko and that, in itself, might have decreased the risk of Alzheimer’s dementia. In a situation like this physical exercise is what scientists call a confounder – i.e. a concomitant but not necessarily casual event that can falsely be seen as a cause resulting in the final effect.

How can one figure this one out? Over the next few columns we will look together at ways of answering apparently not so straightforward questions about physical exercise and the brain.

Now, to begin I will like to make this column, to whatever extent possible, an interactive forum. And that is as it turns out that the brain really likes it when it’s asked to be “active”. Passive audiences, which are spoon fed information, score less well when tested on retention and understanding of the presented material than audiences that were kept engaged through the process. So, in the spirit of “engagement” I will start by asking a few questions about what is important when it comes to the effects of physical exercise on the brain. Depending on what your answers will be we will then take it to the next level, i.e. critically examine the research evidence about specific brain effects of different types of physical exercise.

So, consider which of the following possibilities will get you convinced that physical exercise is good for the brain. Would you be convinced if exercise has been shown to:

1. Increase longevity (as a better brain should make us live longer, shouldn’t it?)
2. Decrease the risk of Alzheimer and other types of dementia
3. Decrease the risk of “normal” age related memory loss or cognitive decline
4. Increase one’s ability to problem solve
5. Decrease one’s risk for depression or anxiety.
6. Improve one’s memory, concentration and attention.
7. Improve one’s ability to feel consistently happy.
8. Increase the number of nerve cells or nerve cells connections in the brain?
9. Correlate with higher education
10. Correlate with higher social economic status?
11. Chemicals released during exercise were shown to promote nerve cell growth?
12. Exercise would “correct” chemical abnormalities reported in mental or brain illness?

I am looking forward to your answers. Please do not hesitate to come up with other questions or hypotheses. We’ll make this into an exercise about how to think about physical exercise. Another form of exercise that might be good for the brain.

– Adrian Preda, M.D. is an Assistant Professor of Psychiatry and Human Behavior in the UC Irvine School of Medicine’s Department of Psychiatry and Human Behavior. His expertise in human behavior, psychology and spirituality is based on years of experience working as a psychiatrist, psychotherapist, teacher and researcher in a variety of academic clinical and non-clinical settings. He also teaches the UC Irvine Extension class The Mind that Changes the Brain: Wellness in the Second Millennium.